The purpose of this project is to investigate the etiology of experimental tumors in the rat bladder. It is hoped to gain an understanding of the nature of the processes of carcinogenesis, determine why these tumors apparently show common cross reacting antigens whereas most chemically induced experimental tumors have unique tumor specific antigens which do not cross react and identify the factors influencing the immunization schedules so that these can be improved. We are also looking for a marker for bladder epithelial cells so that these cells can be differentiated from other cells (i.e. fibroblasts or tumor cells of mesenchymal origin) in both cell culture and sections taken from tumor.